Rubens tube, which is basically a tube with holes on the top, and inside the tube there is compressed gas. Then you light the gas on fire, and play sound through the tube and you will see the sound waves as the flames moving.

Mine is just your standard CiW base with the original TMAC tag color-inverted and put on the left, and sort of barely visible on the ball there's Miss Sakaki's head. I plan on working her into every one of my avatars from now on.